:root {
  --bg-primary: #FDFBF7;
  --bg-surface: #FFFFFF;
  --bg-surface-variant: #F4EFEB;
  --text-primary: #2C1810;
  --text-secondary: #705B51;
  --text-tertiary: #A08C82;
  --accent-terracotta: #D96B43;
  --accent-amber: #E5A93C;
  --accent-espresso: #3C2415;
  --border-subtle: #E8DFD8;
  --card-shadow: 0 4px 16px rgba(60, 36, 21, 0.06);
  --header-height: 60px;
  --bottom-bar-height: 68px;
  --safe-bottom: env(safe-area-inset-bottom, 0px);
  --safe-top: env(safe-area-inset-top, 0px);
}

[data-theme="dark"] {
  --bg-primary: #12100E;
  --bg-surface: #1E1A17;
  --bg-surface-variant: #2A2420;
  --text-primary: #F8F4EE;
  --text-secondary: #B8ADA6;
  --text-tertiary: #7D736C;
  --accent-terracotta: #E27B55;
  --accent-amber: #EEB64D;
  --accent-espresso: #C49775;
  --border-subtle: #362E28;
  --card-shadow: 0 4px 20px rgba(0, 0, 0, 0.45);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  min-height: -webkit-fill-available;
  overflow-x: hidden;
  display: flex;
  flex-direction: column;
}

/* App Header */
.app-header {
  height: var(--header-height);
  background-color: var(--bg-surface);
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  padding-top: var(--safe-top);
  position: sticky;
  top: 0;
  z-index: 100;
}

.brand-section {
  display: flex;
  align-items: center;
  gap: 10px;
}

.brand-logo {
  width: 34px;
  height: 34px;
  border-radius: 9px;
  object-fit: cover;
  box-shadow: 0 2px 6px rgba(0,0,0,0.12);
}

.brand-title {
  font-size: 20px;
  font-weight: 800;
  letter-spacing: -0.5px;
  color: var(--text-primary);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.action-btn {
  width: 38px;
  height: 38px;
  border-radius: 10px;
  border: 1px solid var(--border-subtle);
  background-color: var(--bg-surface-variant);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.15s ease;
}

.action-btn:active {
  transform: scale(0.95);
}

.action-btn.btn-plus {
  font-size: 20px;
  font-weight: bold;
  background-color: var(--accent-terracotta);
  color: #FFFFFF;
  border: none;
}

.aws-logo-btn {
  width: 38px;
  height: 38px;
  border-radius: 10px;
  overflow: hidden;
  border: 1.5px solid var(--accent-amber);
  background-color: var(--bg-surface-variant);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform 0.15s ease;
}

.aws-logo-btn:active {
  transform: scale(0.95);
}

.aws-logo-btn img {
  width: 26px;
  height: 26px;
  object-fit: contain;
}

/* Main Viewport Container */
.main-viewport {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding-bottom: calc(var(--bottom-bar-height) + var(--safe-bottom) + 16px);
}

.tab-view {
  display: none;
  padding: 16px;
  flex-direction: column;
  gap: 20px;
  max-width: 900px;
  margin: 0 auto;
  width: 100%;
}

.tab-view.active {
  display: flex;
}

/* Global Search Bar */
.search-container {
  position: relative;
  width: 100%;
}

.search-input {
  width: 100%;
  height: 44px;
  padding: 0 16px 0 42px;
  border-radius: 12px;
  border: 1px solid var(--border-subtle);
  background-color: var(--bg-surface);
  color: var(--text-primary);
  font-size: 15px;
  outline: none;
  transition: border-color 0.2s ease;
}

.search-input:focus {
  border-color: var(--accent-terracotta);
}

.search-icon {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-tertiary);
  font-size: 16px;
}

/* Hero & Shelf Cards */
.hero-card {
  background: linear-gradient(135deg, var(--bg-surface), var(--bg-surface-variant));
  border-radius: 18px;
  padding: 18px;
  border: 1px solid var(--border-subtle);
  box-shadow: var(--card-shadow);
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.hero-tag {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--accent-terracotta);
}

.hero-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
}

.hero-subtitle {
  font-size: 13px;
  color: var(--text-secondary);
}

.progress-bar-container {
  width: 100%;
  height: 6px;
  background-color: var(--border-subtle);
  border-radius: 3px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background-color: var(--accent-amber);
  border-radius: 3px;
  transition: width 0.3s ease;
}

.resume-btn {
  background-color: var(--accent-terracotta);
  color: #FFFFFF;
  border: none;
  padding: 10px 18px;
  border-radius: 10px;
  font-weight: 600;
  font-size: 14px;
  cursor: pointer;
  align-self: flex-start;
  transition: opacity 0.15s ease;
}

.resume-btn:active {
  opacity: 0.9;
}

/* Sections */
.section-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
}

.section-title {
  font-size: 16px;
  font-weight: 700;
  color: var(--text-primary);
}

.section-count {
  font-size: 12px;
  font-weight: bold;
  background-color: var(--bg-surface-variant);
  color: var(--text-secondary);
  padding: 2px 8px;
  border-radius: 10px;
}

.shelf-horizontal {
  display: flex;
  gap: 12px;
  overflow-x: auto;
  padding-bottom: 8px;
  scrollbar-width: none;
}

.shelf-horizontal::-webkit-scrollbar {
  display: none;
}

/* Document Cards */
.doc-card {
  min-width: 160px;
  max-width: 180px;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: 14px;
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  cursor: pointer;
  box-shadow: var(--card-shadow);
  transition: transform 0.15s ease;
}

.doc-card:active {
  transform: scale(0.98);
}

.doc-badge {
  font-size: 10px;
  font-weight: 800;
  text-transform: uppercase;
  color: var(--accent-terracotta);
}

.doc-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  line-height: 1.3;
}

.doc-meta {
  font-size: 11px;
  color: var(--text-tertiary);
  margin-top: auto;
}

/* Course Grid */
.courses-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 12px;
}

.course-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: 16px;
  padding: 14px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  cursor: pointer;
  box-shadow: var(--card-shadow);
}

.course-icon-badge {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  margin-bottom: 4px;
}

.course-code {
  font-size: 15px;
  font-weight: 800;
  color: var(--text-primary);
}

.course-name {
  font-size: 12px;
  color: var(--text-secondary);
  line-height: 1.3;
}

/* Reader View */
#reader-view {
  padding: 0;
  height: calc(100vh - var(--header-height) - var(--bottom-bar-height) - var(--safe-bottom));
  position: relative;
  overflow: hidden;
}

.reader-toolbar {
  height: 48px;
  background-color: var(--bg-surface);
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 12px;
  font-size: 13px;
}

.reader-title {
  font-weight: 600;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 180px;
}

.reader-canvas-container {
  flex: 1;
  height: calc(100% - 48px);
  overflow-y: auto;
  overflow-x: hidden;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 12px 0 80px 0;
  gap: 12px;
  background-color: #525659;
}

.pdf-page-wrapper {
  background-color: #FFFFFF;
  box-shadow: 0 4px 12px rgba(0,0,0,0.25);
  display: flex;
  justify-content: center;
  max-width: 100%;
}

.pdf-page-canvas {
  max-width: 100%;
  height: auto !important;
}

/* Paper comfort filters */
.paper-sepia .pdf-page-canvas {
  filter: sepia(0.35) contrast(0.95);
}

.paper-dark .pdf-page-canvas {
  filter: invert(0.9) hue-rotate(180deg);
}

/* Floating Reader Page Pill */
.reader-page-pill {
  position: absolute;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  background-color: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: 20px;
  padding: 6px 14px;
  display: flex;
  align-items: center;
  gap: 10px;
  box-shadow: 0 6px 20px rgba(0,0,0,0.18);
  z-index: 50;
  font-size: 12px;
  font-weight: 600;
}

.reader-slider {
  width: 110px;
  accent-color: var(--accent-terracotta);
}

.page-jump-input {
  width: 38px;
  height: 26px;
  border-radius: 6px;
  border: 1px solid var(--border-subtle);
  background-color: var(--bg-surface-variant);
  color: var(--text-primary);
  text-align: center;
  font-size: 12px;
  font-weight: bold;
}

/* Bottom Navigation Bar */
.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: calc(var(--bottom-bar-height) + var(--safe-bottom));
  padding-bottom: var(--safe-bottom);
  background-color: var(--bg-surface);
  border-top: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: space-around;
  z-index: 100;
}

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  color: var(--text-tertiary);
  cursor: pointer;
  background: none;
  border: none;
  width: 68px;
  transition: color 0.15s ease;
}

.nav-item.active {
  color: var(--accent-terracotta);
}

.nav-item svg {
  width: 22px;
  height: 22px;
  fill: currentColor;
}

.nav-item span {
  font-size: 11px;
  font-weight: 600;
}

/* Modals */
.modal-overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.6);
  display: none;
  align-items: flex-end;
  justify-content: center;
  z-index: 200;
}

.modal-overlay.active {
  display: flex;
}

.modal-sheet {
  background-color: var(--bg-surface);
  width: 100%;
  max-width: 500px;
  border-radius: 20px 20px 0 0;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  box-shadow: 0 -4px 24px rgba(0,0,0,0.25);
  padding-bottom: calc(24px + var(--safe-bottom));
}

.modal-title {
  font-size: 18px;
  font-weight: 800;
  color: var(--text-primary);
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
}

.form-input, .form-select {
  height: 42px;
  padding: 0 12px;
  border-radius: 10px;
  border: 1px solid var(--border-subtle);
  background-color: var(--bg-surface-variant);
  color: var(--text-primary);
  font-size: 14px;
  outline: none;
}

.modal-actions {
  display: flex;
  gap: 10px;
  margin-top: 8px;
}

.btn-secondary {
  flex: 1;
  height: 44px;
  border-radius: 12px;
  border: 1px solid var(--border-subtle);
  background-color: transparent;
  color: var(--text-primary);
  font-weight: 600;
  cursor: pointer;
}

.btn-primary {
  flex: 1;
  height: 44px;
  border-radius: 12px;
  border: none;
  background-color: var(--accent-terracotta);
  color: #FFFFFF;
  font-weight: bold;
  cursor: pointer;
}

/* Offline Banner */
.offline-banner {
  background-color: var(--accent-amber);
  color: #2C1810;
  font-size: 12px;
  font-weight: bold;
  text-align: center;
  padding: 4px;
  display: none;
}

.offline-banner.visible {
  display: block;
}